Field of the Invention
The present invention relates to an image forming apparatus.
Description of the Related Art
Conventionally, in an electronic device such as an image forming apparatus, to control actuators such as stepping motors, DC brushless motors, or the like arranged in respective locations, CPUs or ASICs for outputting control signals of motors are arranged by being distributed on a plurality of substrates. In a case of such an arrangement, for connection between a main CPU for outputting an overall control timing instruction for causing rotation of each motor and CPUs or the like arranged on each substrate, 2-line type and 3-line type serial communication modes are commonly used for transmitting with fewer signal lines (for example, Japanese Patent Laid-Open No. 2011-186231).
Conventionally, as a method for causing driving of CPUs or the like connected by a serial communication signal line arranged on each substrate, a method for connecting each substrate to a quartz oscillator, a method for providing a CLK signal on a communication signal line and driving by the CLK signal, or the like are used.
In a case of a configuration that connects the CPU or the like of each substrate to a quartz oscillator, a cost in proportion to the number of quartz oscillators is incurred. In addition, in the case of a method for transmitting a CLK signal together with a serial communication signal, there are problems such as radiant noise, a CLK signal line cost, and operation instability due to external noise on a transfer path.
Accordingly, a configuration for performing control by using an integrated oscillator that is integrated in a CPU or the like as illustrated in FIG. 1 is can be considered. In this configuration, an integrated oscillator and a CPU are provided in each of a main substrate and a sub substrate, and control of a DC brushless motor or a stepping motor connected to each is performed.
Generally an integrated oscillator has a low cost compared to an external quartz oscillator, and is superior from a cost perspective. However, generally, for an integrated oscillator, there is a significant tendency of a change of a frequency characteristic with respect to temperature in comparison to a quartz oscillator. Therefore, in a case of using integrated oscillators to perform control for which precision is necessary for CPUs or the like arranged dispersed on substrates installed at places where the temperature is different in an image forming apparatus, problems arise due to differences of operation due to environmental temperatures of the plurality of integrated oscillators.